This invention relates in general to knitting machines and methods and, more particularly, to a new and useful machine for the production of knitted goods having means for displacing at least two groups of thread guides around a common pivot axis and for displacing the groups of thread guides relative to each other along the pivot axis and a method of operating the machine.
U.S. Pat. No. 4,009,597 discloses a warp knitting machine, for the production of knitted goods, which includes a row of tongue needles, that is, needles which at one end of their shank have an opening which is partially bounded by a tongue articulated to the shank. A warp thread guide is provided for each needle. The warp thread guide, in operation, lays a warp thread around the needle into the opening thereof so that a stitch loop chain is formed out of each warp thread. Weft thread guides are provided, through which the weft threads are laid in, which extend transversely to the stitch loop chains and connect these with one another. Furthermore, two thread guides are provided for weaving, at both longitudinal edges of the knitted articles respectively, an additional thread into the outermost pair of stitch loop chains. Both of these additional threads prevent ravelling of the finished knitted article on the tearing of a thread disposed at the edge. Each of both these additional threads is laid around the two outermost needles each time a row of stitches lying beside one another is formed.
The thread guides for the warp thread and those for guiding the mentioned additional threads are secured to different bars. Drive means not particularly described move these two bars in such a way that a knitted portion of the above mentioned kind is formed of the warp threads and the additional threads. Thus, presumably, the drive means comprise a separate shifting and separate pivoting mechanisms for each of the bars, wherefore they are relatively complicated. Therefore, at each of the longitudinal edges of the knitted article, a formation of double stitches is made during each stitch formation at both the outermost stitch loop chains.
Such a formation of double stitches is however only possible when the machine is equipped with tongue needles as already mentioned. Certain types of machines are, however, equipped with crochet needles, that is, with needles which at one shank end include an elastically deformable hook, which is contiguous with the shank and the free end of which is bent back to the shank and bears resiliently on one side thereof. It is not possible on a machine, which displays crochet needles of that kind, to lay an additional thread into two needles in the same operating cycle in such a manner that double stitches of the previously known kind are formed.
When the stitch loop chain pairs, disposed at both longitudinal edges of an article, are connected with one another only through a respective woven-in additional thread, the knitted article is not reinforced in its interior between these edges. Although U.S. Pat. No. 4,009,597 discloses that additionally double stitches could be formed also in interior stitch loop chains, that is, not lying at the edge, this method would also, however, still have the disadvantage that the stitch loop chains are continuously connected only, in pairs, with one another by the additional threads over the entire length of the knitted article. Thus, if the different stitch loop chain pairs were then also connected with one another only by the weft threads, which would for example be unfavorable in a wale tape for the formation of a closure with two tapes which display wale loops that are hookable into one another.
Furthermore, in British patent specification No. 1,527,123, there is a knitting method, in which stitch loop chains formed of basic warp threads are connected with one another by weft threads extending transversely to them and additionally by additional warp threads which are alternately worked into the stitches of two different stitch loop chains. In that case, the basic warp threads, as well as the additional warp threads, are alternately laid in different rotational sense around the needles. Such a manner of operation is, however, likewise not possible with crochet needles, but only with needles which display either an articulated tongue or a slide.